Signaling apparatus



AMay 12, 1931. H. o. HoLTE 1,805,092

` SIGNALING 'APPARATUS Filed June 26, 1926 lll/l/lll/llllllllllll/lllllllll/ll/l/ l #f4 ATTORNEY K phragm D to vibrate.

- pressed upon the air in the brake pipe may be Patented May Y 12, 1931 i UNiTED STATES vPATENT ori-ICE f HAROLD O. `HOL'IE, DECEASED, LATE OF- PITTSBURGH, PENNSYLVANIA, BY HALVOR HOLTE, ADMINISTRATOR, vOF GROOKSTON, MINNESOTA, .ASSIGrNOR TO THE' TIILI'IOAT,` v SWITCH & SIG-NAL COMPANY, OF SWISSVALE, PENNSYLVANIA, .A'CORPORATIONV OF PENNSYLVANIA Application led `Tune 26,

This invention relates to signaling apparatus, and particularly to apparatus for signaling between two points on a railwaytrain, such, for example, as between the locomotive and thecaboose of a freight train, or between the locomotive at theY front and a second locomotive at the rear of the train.

Two forms of signaling apparatus embodying this invention will rbe described, and the novelY features thereof will then be pointed out in claims.

In the accompanying drawings, Fig. 1 is a view, partly diagrammaticA and partly sec-l tional, showing one form of signaling apparatus embodying this invention. Fig. 2 is a plan view of the diaphragm for a microphone shown in Fig. 1. Fig. 3 is a sectional view of a portion of a vibration relay structure shown in Fig. 1. Fig. 4E is a diagrammatic view showing a modified form of signaling apparatus also embodying this'invention.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. 1, the-apparatus comprises an air signal receiving mechanism in which a brake pipe A is connected to a microphone M in such manner thatvibrations in the air in the brake pipe will cause a dia- The vibrations improduced by any suitable `mechanism such, for example, as that shown in copending application of Harold O. Holte Serial No.

n 21,550, filed April 8, 1925, for signaling apparatus.

The microphone M comprises a` casing 1,- divided into two compartments 2 and -3 by means of the diaphragm Dwhich is thin and exible. The compartment 3 contains an insulating cup 4 filled ywith carbon granules 5 which are adapted to vary'the electrical resistance between a stationary electrode 6 and an electrode 7 mounted ontlie diaphragm D. The front wall `13 of the compartment 2 is vprovided with apertures 8 and`9 which afford communication between compartment 2 and a compartment 10' which is open to the brake pipe A. The wall13 is provided with stops 14 in proximityto opening 9 to limit theA i movement ofjelectrode 7 ,'andlso toepreventA SIGN ALING l APPARATUS 1926. Serial No. 117,314. y y

back wall of compartment 3 contains a port 11 which communicates with a closedV volume 12 of suitable size.v It will thus be seen that the diaphragm D is exposed on one side to the air in the brake pipe A, and on the other side to the closed volume y12 through the port 11. y

For low signaling frequencies the [diaphragmy D is preferably made of thin soft rubber provided with slits S1 (Fig. 2) and it is stretched in such a way as to hold thesel slits closed. The slits prevent the diaphragm from kbeing ruptured by pressure changes caused by air brakeapplication and release, yet for small pressure changes, suchV as those due to a weak signal the slitsare substantially closed. vIn order to prevent the diaphragm D from being torn by aY sudden and very large pressure change such as would be caused byJ any emergency brakey application, two flap valves V which are mountedat opposite ends of port 11, are provided. -A large flow of air will cause one or the other of these valves t0.Y close and then leak slowly until the pressures on the two sides of the diaphragm D are equalized. 1

' The electrodes 6 and 7 of microphone M and a battery B, are connected in series with the winding 16 lof an, untuned or highlyl damped vibration relay H having anarmature 1,8. The armature 18 operates a contact .21* 22' which is connected in series with a tuned vibration relay K havingawinding 23, anarmature 26, and contacts 27 and 28. Thecontact 2,6-28 of relay K controls a relayl 29 having its contact 30 in circuit with battery 31 and a signal L. l y For the purpose of rendering the -operation of contact 21h-22 independent of .the average microphone current, the relayI-I is provided with an automaticy zero adjuster VZ, Iwhich is: more clearly shown in Fig. 3. An annulus N carries two soft rubber diaphragms 19 and 20. The diaphragm 19 is connected to the armature 18 so that when the armature oscill latesthe diaphragm 19 will be periodically deflected toward the ,diaphragml to coin-` press the air enclosed between the :diaphragme and close .contact 21--22 The volume of air r between the two diaphragmsnis open tothe...

atmosphere through a port P. The pressure of the air is substantially independent of slow changes in volume, thus whatever the meanposition of diaphragm 19 may be, due to diierent values'of'direct current in Vibration relay -H,zthe meanposition. of diaphragm 20 will e its normal undeflected position, hence the spacing between contact members 21 and'22maybe Very small. The Contact member 22may'be adjustable and is shown withadjusting'threads for co-operation with a suitable support. The port P in annulus N is `made sufficiently small, so that for the desired operating frequency there will notbe much leakage through it,'hence the deflections of`19 willbe-communicatedvto 20wdue=to the elasticity-,of theairand thus operate contact2122- Vfllheuseofthis adjuster makes vit vunnecessary to use a transformer, and eliminatesthe defects' caused by the variation ofrithe .mean value l'of microphone current which results from the use of a relay directly in series iwith I,the microphone.

y In orderfto 'makefthe apparatus substantially .immune tto interference which would cause foreign vibrations lin the brake pipe not ,intended for signals, the vibration relay K which isftuned and proportioned in such manner that lthecontacts for operating the signal .will onlyfbeclosed when` two rimpulses properly ,spacedin l,time l-are impressed upon it,.is provided. ,Thisresult is accomplished byplacingzaresistance R in `series .with the winding 234.and;contact,2122. The resistance Ris of such value that no matter how long contact 21-22 may be closed the current in .winding`23 .will be insufficient to bring armature26finto contact witlr28. The circuit for winding-23 under this condition is from battery B.t-hrough resistance R, winding 23, contact 22-21 of adjuster Z and wire `24: to'battery B. When ,contact21-22 opens, armature,26,is releasedvand on itsback swing makescontact. at. 27. If, contact 21-'22 closes again while contact is made at27 a circuit is ,completedfrom battery B, through wire 25,:armature26, contactf27, winding 23,- contacti22-21,.and wire.2l back to battery B, thusfshunting t out .the resistance R. Under these .conditions 'winding 23 will get a larger current impulse which is sufficient toclose contact 21S-28, and this will energizeirelay 29 which controls .the -Ysignal L.

Due `to `the'.characteristics'of a brake pipe as .antransmission 'mediumit is necessary to use a .comparatiyely low `frequency `for transmittingsignals througha long train. Inorder ,tofmake the. signal-Loperate continuously over theltime. of agroup of cycles the relay V29 i-may -be slowreleasingso' that `it will hold over frompnefcyc'le to the -neX-t. 'The contact; 2728fmay ope-rate the signal -L directly, in thaticaseithe indication will; be of the same fmquencynstheiair rbratonsand the Judge mhetherft ,istduezto the pulsations impressed upon the air in brake pipe A, strikes the diaphragm D causing it to Vibratewith thesame'frequency as that ofthe vimpressed waves,' the resistance ofthe circuit through battery B and winding '16 of relay H is varied and a pulsating'direct current is therefore'supplied to relay H. Armature 18 is set into vibration causing Contact 21-22 to be opened and closed at a rate depending upon the frequency ofithe signaling waves. Relay 1K is tunedfto respond-to current. of the frequencysupplied bythe transmitter, hence on-thefirst back swing of armature 26, contact 26-27 willbeclosed to -shunt-out-resist ance R. Contact 21-22 will close while-,contact 26-27 is closed so thatsuicientcurrent will Howto-winding 23 to closev Contact 26-#28 and energize relay 29. `Contact-8O willclose and signalL will-be supplied withcurrent from battery 31. After energization-of 'relay 29,-.contact 26--28 will open again vdue l:to opening'of contact 21-22, but -due to the slow acting characteristics of relayA 29 itwill hold over "fromlone 'pulsation -to the neXt as long aspu'lsationsof-signalingfrequencyfare supplied to relayH, so that Contact 30 will notfbe released duringthe time between the periodic opening and closing of contact 26'-28. If atrain of Vwaves of a frequency dierent vfrom lthe ysignaling frecpiency chosen, should impinge upon diaphragm -D the contact26r28 of relay K could -Vonly be closed if two vinterfering` impulses properly spaced in time according to thetuning of relay -K :shouldoccur, hence the system will be substantially free from interferenceydue to foreign Vibrations.

In Fig. 4 is shown amodiied 1forni.of.receiving apparatus in which all of the Vparts with thee'Xception of-the tuned vibration relayK1 lare :the lsame yas those illustrated in Fig. 1.

'llher'e'layLK1 comprises a winding, anvarmature 37 co-acting with contacts 39 and .4.0, andtworesistances 34 and 38. Contact 37-39 is normally closed when contact21-22 yis closed, the current rflowing from 'battery B through wire V32,; and then` dividing between two branch circuits, one passing through winding SBTand the other including wire l25, contact-87-39, and resistance `38. Thecurrent from fthe -two vbranch ycircuits passes through resistance 321, contact 22-.21 and wire-24 backtof battery B. Theproportioning of parts r,is :such lthat when vcontactv y,22--21 opens, the backward-swing of armature 37 willv 'not fclose Contact LAt-10, but if contact 22-f21elojses tw'hilecontact37 -V-;3-9isfop,en-;t1ie cur-rent ffrom `battery B `:will f p'azss ,dirertly through wire 32 and winding 33, the branch circuit through resistance 38 being open at contact 37-39. Under these conditions the current supplied to the winding 33 will give the armature 37 a larger impulse so that on its backward swing it will close contact 37-40 yto pick up the relay 29 and operate signal L.

When contact 37-40 is closed, current flows from battery B through wires`32 and 25, contact 237-40, relay 29, and wire 24 back to battery B. It will thus be seen that contact 37-4O can only be closed when two interfering impulses properly spaced in time are supplied to relay K1. .The relay 29 is arranged to hold over from one impulse to the next in the manner described with reference to Fig. l.

Although there is shown and described but two forms of signaling apparatus embodying this invention it is understood that various changes and modifications may bek made therein within the scope of thek appended claims without departing from the spirit and scope of the invention.

Having thus described the invention what is claimed is:

l. A fluid pressure responsive device comprising a chamber having an opening communicating with a uid pressure system, a

thin diaphragm stretched across said chamber and provided with slits which are normally closed but which open in response to severe pressure changes in said system, and a microphone having two coacting members one of which is attached to said chamber and the other to said diaphragm.

2. A vfluid pressure responsive device comprising a chamber having two openings one of which communicates with a Huid pressure system, a closed.y reservoir communicating;y

with the other opening,la flap valve at each end of said second opening, a diaphragm stretched across saidk chamber between said v two openings, and a microphone having two coacting members one of which is attached to said chamber and the other to said diaphragm.

3. A Huid pressure responsive device comi prising a chambery having two openings one of which communicates with a fluid pressure system, a closed reservoir communicating with the other opening, a flapvvalve at each end of said second opening, a thin diaphragm stretched across said chamber between said two openings and provided with slits which are normally closedv but which open in. response to severe pressure changes in said system, and a microphone having two coacting members one of which is attached to said chamber and the other'to said diaphragm.

In testimony whereof I aiiiX my signature.

i HALVOR HOLTE,

Administrator of Harold .0. Holte, deceased. 

